Freeze Drying
Harvesting and storing food is just as interesting as growing it. Freeze Drying is one way to preserve food. Let's take a look at it.
Freeze Drying
Freeze Drying is a process that eliminates water from substances like food or herbal preparations. There are three principal phases:
- Deep Freeze (-40F)
- Drop Pressure to Vacuum
- Gradually Heat Food, sublimating water directly off substances and capturing it on outside of the freezer.
The machine takes the substance through these phases/temperatures a few times to complete the drying process.
After completion, the trays of freeze dried food are removed. All the water that was in the substance is now frozen to the inside of the freeze dryer. You can engage a "defrost" mode which uses the tray heaters to bring the chamber to 140F, which can blast through the defrost process in ~ 2 hrs. This can be accelerated greatly by manually breaking/pulling off the ice once the thaw starts a bit. This is the only critical step that has to be performed between loads.
Components
Corresponding directly to those three steps, there are three principal components in the freeze dryer:
- Deep Freezer (lots of Amps)
- Vacuum pump (lots of Amps)
- Heated Trays (... lots of Amps)
As you can tell, these beasts draw quite a heavy load -- peaking at 16A when all three components are on (in practice, trays are only heated intermittently to gradually draw out hydration).
Tips
- The freeze dryer is typically tilted slightly back to drain off water.
- When doing a load of liquids (i.e., raw eggs, yogurt, whatever), level the unit so liquid doesn't pour off the trays into the chamber.
